The asymptotic behaviour of Eq. (REF ) for \(V_x\ne c_x\)  is provided in [1]} (under the simplifications used above) as
\(h(x,t)\big |_{V_x\ne c_x}\sim \left(\frac{AB^{\frac{1}{2}}2^{\frac{3}{2}}}{\sqrt{2\pi }|V_x-c_x|^{\frac{5}{2}}}t^{-\frac{1}{2}}\right)\cos \left[\left(\frac{|V_x-c_x|}{2}\right)^2\frac{t}{B}+\frac{\pi }{4}\right]\\+O(t^{-1})\quad \text{ as } t\rightarrow \infty .\) 
